[FFmpeg-devel] [PATCH 3/3] avutil/opt: Preserve nb_channels in opt_free

[Michael Niedermayer]

Fixes: division by 0
Fixes: decoder modifying demuxer channels on failure
Fixes: -sseof -5 -i zgclab/ffmpeg_crash/poc3

Found-by: Wang Dawei and Zhou Geng, from Zhongguancun Laboratory
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavutil/opt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavutil/opt.c b/libavutil/opt.c
index ecbf7efe5fb..24c08e4bc06 100644
--- a/libavutil/opt.c
+++ b/libavutil/opt.c
@@ -132,9 +132,11 @@ static void opt_free_elem(const AVOption *o, void *ptr)
         av_dict_free((AVDictionary **)ptr);
         break;
 
-    case AV_OPT_TYPE_CHLAYOUT:
+    case AV_OPT_TYPE_CHLAYOUT: {
+        int nb_channels = ((AVChannelLayout *)ptr)->nb_channels;
         av_channel_layout_uninit((AVChannelLayout *)ptr);
-        break;
+        ((AVChannelLayout *)ptr)->nb_channels = nb_channels;
+        break;}
 
     default:
         break;
-- 
2.43.2